Field of the Invention
The present invention relates to an imaging device-packaging method to mount an imaging device chip which is provided in a tip portion of an endoscope on a flexible substrate. Further, the present invention relates to an endoscope-assembling method using the above packaging method, an imaging module, and an endoscope.
Description of Related Art
An endoscope (an electronic endoscope) is known of a type in which an imaging device is provided in a tip portion of the endoscope, wiring is drawn out from the imaging element, and image information is converted into an electric signal which is then transmitted. In such an endoscope, a substrate with the imaging device mounted thereon is inserted into a tubular scope tip portion (refer to, for example, Patent Documents 1 to 3 (Japanese Patent No. 3216650 (hereinafter, Patent Document 1), Japanese Unexamined Patent Application, First Publication No. S61-50544 (hereinafter, Patent Document 2), Japanese Unexamined Patent Application, First Publication No. S61-254917 (hereinafter, Patent Document 3)).
In Patent Document 1 (refer to Paragraphs 0032 to 0045, in particular, Paragraphs 0033 and 0044), an electronic endoscope is described in which an imaging device is mounted on a central plane portion of a flexible circuit board bent into a U-shape and the diameter of an insertion portion is reduced.
In Patent Document 2, an endoscope is described which has an imaging device electrically connected to one end portion of a bent flexible printed circuit board and is accommodated in a tubular body.
In Patent Document 3, an endoscope is described in which a prism is directly bonded to an element surface of an imaging device without interposing a cover glass therebetween.
In the endoscopes described in Patent Documents 1 and 2, the imaging device is mounted on the flexible board. In Patent Document 1, if wire bonding is used for electric connection of the flexible board and the imaging device, it is necessary to increase the size of the endoscope (refer to Paragraph 0008 of Patent Document 1), and thus the imaging device and the flexible board are connected by a method to reduce the size of the endoscope, such as performing conductive connection by a lead frame in a state where the flexible board with the imaging device mounted thereon is bent (refer to Paragraphs 0035 and 0040 of Patent Document 1).
In the endoscope described in Patent Document 2, although there is no clear statement in the specification, according to FIG. 2 of Patent Document 2, it is considered to be a structure in which an image element chip is packaged, similar to FIG. 17 of Patent Document 1.
In the endoscope described in Patent Document 3, wiring is directly connected to an input-output terminal of the imaging device.